8500 lbs is a lot of weight for your 1/2 ton. I don't think your hitch will level it out because the trucks frame can't bend that much. It's best to try it out first on a dry run.
Keep an eye on your rear end temps towing that much weight. My 07 chevy 1500, and 2010 Ram's rear end overheated towing 8000# up long grades. (had to buy oversized Maghytec differental covers)